Cleaning carb jets and passages

turbofiat124

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I realize this is not a lawnmower but is motorized and has some relationship.

Now in addition to my Tomos TX-50, I have a new toy.

A co-worker gave me a kid's four wheeler the other day. I'm going to fix his Yamaha Bruin 350 in trade.

The bolt that holds the swing arm to the chassis broke and the rear shock is busted. In the meantime I have a bungee cord wrapped around the frame and luggage rack to keep the shock from coming apart if I the suspension decompresses.

Since it had been sitting for about 6 years in a storage building, the carburetor had to be thoroughly cleaned out. This was one of the worst carbs I had ever seen as far as being gunked up. The brass bits had turned green and had some buildup on them. There was some green funk that had settled in the bottom of the fuel bowl. Kerosene and a wire brush wouldn't remove it.

I put all the brass bits in my bead blaster including the float bowl to remove this green funk. I know when acid comes in contact with brass it will turn it green. I didn't know gasoline was acidic. Most of the time the inside of the carb turns a crusty white.

But what was really a pill was the main and idle jets. I tried soaking them in Outlaw fuel injection cleaner but nothing seemed to cut it. I tried compressed air, copper stranded wire as a pick. The only thing that seemed to work was hitting the main and idle jets with a propane torch. This black stuff started to ooze out after awhile. Eventually I was able to clean them out.

I figured if I couldn't get the carb cleaned up, I didn't have anything to lose. These carbs are not that expensive.

Anyone seen clogged jets this bad and where all the insides had turned green?

But I finally got it running:

https://www.youtube.com/watch?v=qyoHXaNn7Pk
 

ILENGINE

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The ethanol/water mix from todays gas when combined with other things in the air/ fuel form a mild acid. The green junk could be stale gas varnish mixed with algae. The white powder in the carb is due to water corroding the aluminum.
 

turbofiat124

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I think this ATV is a copy of a Honda. Either they made an illegal copy of it or they bought they tooling from Honda when they were done with it. I've got an AC generator that has what is known as a Chonda engine. Which is a Chinese copy of the widely produced Honda 5.5hp side shaft engine.

It seems the Chinese have perfected the art of reverse engineering but when it comes to actually building what they copy, then cheapen the hell out of it. I'm surprised their own missiles and bullets don't blow up in their damn faces.

My friend gave me this thing because he said he was tired of messing with it due to it's poor build quality. I've got a blue pocket bike and the build quality on that thing is horrible. The Chinese do not know how to add lock washers or Lock-tite on anything. Two of the three bolts that holds the recoil starter to the engine fell out. So when I yanked on the starter, the remaining bolt pulled the tab off the engine block! What's ignorant is the starter is plastic. I've never seen plastic that was stronger than aluminium! Luckily it being porous I was able to apply some 2 part epoxy and so far it has held up!

This carburetor baffles me. I'm guessing it's also a copy of either a Keihin or Mukini. It actually has Japan stamped on the throttle neck but could just be the name of the factory or mean absolutely nothing. There was some urban legend ages ago the Taiwanese built a plant called "USA" to make it appear their products were made in the "U.S.A". Like those MEMEX cassette tapes and Sharpei markers.

http://www.ebay.com/itm/191924870149?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

It's similar to my Dellorto on my Tomos TX-50. On that carburetor there is no idle mixture screw but the bike runs fine. The Italians and Yugoslavians build better stuff than the Chinese!

When I pulled the idle mixture and speed screws out of this ATV carburetor, instead of them being tapered like a typically needle valve, both look like dummy plugs. The end on one is like a ball. What's weird is I can remove the idle mixture screw completely and it has no effect whatsoever. By all accounts the engine should lean out and stall.

I'm also not 100% sure if what I am seeing is un-burned fuel or burnt oil. The oil level does is not changing but the smoke looks blue to me. On the first day I got this thing running it was 61F. In typical Southeastern US weather fashion, the next day the temperature was 34F. On the 61F day (the day the video was taken) I did not see any smoke but the next day I did. I don't think it was condensation I was seeing because it never went away after an hour of riding. My friend says this thing probably has less than 20 hours on it. One guess could be a stuck ring from where it has sat for so many years. Maybe I need to pull the intake manifold and fill the cylinder and crankcase full of PB Blaster and let it sit over night.

The second day I tried to start it but it wouldn't start so I pulled the spark plug and it looked carbon fouled to me. After I bead blasted it, it fired up. My guess is as long as the engine is hot, the plug will fire but not when cold?

I tried starting it this morning before leaving for work (~25F) and it tried to start once but couldn't get it going.

I can't figure out why removing the idle mixture screw has no effect and if the engine is running too rich, why. Unless it has something to do with the float level.

I just got to verify the distance between the mounting holes is 48 mm and the venturi is 19mm before ordering a new one. At $14 + free shipping from a US supplier, it's almost not worth messing with.

Any ideas?
 
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